Linoleic Acid.

What it does

As a lightweight emollient it supports the moisture barrier and is the 'kinkier,' less greasy counterpart to oleic acid.

Benefits

• Skin-identical fatty acid that helps build and repair the moisture barrier (precursor to acylceramides)
• Lighter and less greasy than oleic-rich oils, so it is the more breakout-friendly fatty acid
• Acne-prone skin tends to have lower linoleic acid in its sebum; a topical 2.5% linoleic acid gel reduced microcomedones by about 25% over four weeks in one study
• Some data for anti-inflammatory and mild skin-lightening (UV-induced pigmentation) effects

Side effects

• As a polyunsaturated oil it oxidizes (goes rancid) relatively easily, which can make it less stable in formulas
• Even though it is the more acne-friendly fatty acid, it sits within the C11-C24 range that lipid-dependent Malassezia yeast can use, so pure fatty-acid sources are still commonly flagged as a possible fungal-acne (Malassezia folliculitis) trigger

Who it's for

Acne-prone, barrier-impaired, dehydrated, or generally most skin types

Who should be careful